[easytag] Improve handling of empty image files

[David King <davidk src gnome org>]

commit 0d265c866d29c541e4c1d3c32e3995503a72c0a2
Author: David King <amigadave amigadave com>
Date:   Wed Jul 29 23:39:36 2015 +0100

    Improve handling of empty image files
    
    Raise an error, avoiding a crash, when an image file is empty.
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1248194

 src/picture.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/src/picture.c b/src/picture.c
index f661d04..d11dc0a 100644
--- a/src/picture.c
+++ b/src/picture.c
@@ -469,6 +469,16 @@ et_picture_load_file_data (GFile *file, GError **error)
 
         g_assert (error == NULL || *error == NULL);
 
+        if (g_memory_output_stream_get_data_size (G_MEMORY_OUTPUT_STREAM (ostream))
+            == 0)
+        {
+            g_object_unref (ostream);
+            /* FIXME: Mark up the string for translation. */
+            g_set_error (error, G_IO_ERROR, G_IO_ERROR_INVALID_DATA, "%s",
+                         "Input truncated or empty");
+            return NULL;
+        }
+
         bytes = g_memory_output_stream_steal_as_bytes (G_MEMORY_OUTPUT_STREAM (ostream));
 
         g_object_unref (ostream);